1. Technical Field
The present invention relates generally to wireless communication devices and in particular to wireless communication devices utilized in computer systems. Still more particularly, the present invention relates to customer installable and replaceable U-NII wireless cards utilized in computer systems.
2. Description of the Related Art
Computer-based wireless communication devices, including wireless LANs and wireless ready systems, is a quickly emerging and evolving technology. Conventional computer-based wireless communication devices transmit radio frequency (RF) signals to wireless receivers of local area networks (LANs). These devices include transmitters that both transmit and receive wireless communication within a particular bandwidth in the highly regulated RF spectrum.
The RF spectrum is a limited bandwidth spectrum that is allocated among a number of different services types/applications, including military, aviation, broadcast, and commercial communications. Because of the very limited bandwidth available within the radio frequency (RF) spectrum, transmission in this medium is subject to strict government regulations. The regulations typically cover to the type and parameters of the transmitters being utilized in a wireless network. These regulations cover modulation scheme, frequency of operation, and transmit power of the transmitters in order to avoid interference among the various authorized services utilizing the RF spectrum.
Transmitters comprise a combination of a circuit module called a radio coupled to an antenna. The antenna is a central part of the transmitter since the antenna is designed and tuned to optimize gain or attenuation for desired frequencies. Conventionally, manufacturers of transmitters obtain a license from the government authorizing the manufacturer to manufacture a particular type of transmitter, exhibiting particular parameters. The license covers both components of the transmitter unit (i.e., radio and antenna), and the license typically specifies exact protocols (i.e., operating parameters or ranges of parameters) for both components and the combination device. In the United States, for example, licenses are granted and regulated by the Federal Communication Commission (FCC). Also, the regulations require that the end users not be able to change or reconfigure the transmitter, which would result in operation outside of the authorized parameters. Any change made to the operating parameters radio or antenna requires another application for license and authorization by the FCC.
Conventional wireless computer networks are provided two frequency ranges with defined protocols to support wireless operations. These protocols are the 802.11b and 802.11g protocols, operating at ISM band for 2.4 GHz, and the U-NII HiperLAN/2 and other protocols, operating at U-NII for 5 GHz. With the strict government regulations, it is essential that manufacturers and users of Wireless Fidelity (WiFi) LAN components ensure that the wireless component is operating within authorized parameters (i.e., power, roll off, etc. as defined by specification) provided by the ISM band for 2.4 GHz and U-NII for 5 GHz ranges. It is also essential for the components to be designed to prevent tampering or modification by the end users, which would change the operating parameters of the transmitter.
To obtain authorization for the transmitter, manufacturers implement design and manufacturing controls to ensure that the transmitter complies with the regulatory requirements. For example, the regulation of transmitters operating with the ISM 2.4 GHz band requires a unique connection between the radio and antenna. To satisfy this requirement, the manufacturers designed a unique connector. International Business Machines Corporation, for example, selected a reverse thread connection for its low profile peripheral component interconnect (PCI) Card. That company also implemented a method referred to as BIOS Lock, which is described below to ensure compliance with the FCC's ISM 2.4 GHz band regulations.
Maintaining tight coupling between the radio and antenna in desktop personal computer or with PCMCIA cards is straightforward, since transmitters (radio and antenna) are typically packaged as a single unit within the casing of the card. However, maintaining tight coupling for devices imbedded in notebook-type computer systems is much more complicated because the antenna is integrated into the lid portion or cover (i.e., within the external plastic or composite shell covering the top portion) of the portable computer system, while the radio is typically a mPCI (mini peripheral component interconnect) card inserted into the lower portion (i.e., the base/chassis) of the portable computer system. In the portable computer environment, the transmitter is assembled by inserting the wireless PCI card into an mPCI slot and attaching the radio to the antenna via coax cable leading to the antenna imbedded in the lid portion.
Since there are a variety of suppliers of 802.11b mPCI (ISM 2.4 Ghz band) cards available on the market, the manufacturers of the notebook computer systems have to implement ways to ensure that the FCC regulations are complied with. That is, the manufacturer must design the computer system with a built in mechanism to prevent unauthorized 802.11b cards from being utilized with the antenna built in to the computer system's cover. Different manufacturers provide different methods of handling this potential problem. IBM, for example, currently implements a method referred to as BIOS (basic input/output system) Lock, which is described below.
Conventional 802.11b mPCI cards are inserted into the computer system before the computer system is powered on, and as such, BIOS Lock occurs during boot-up of the computer system. During boot, power-on self test (POST) checks the PCI IDs of the mPCI card and compares it to authorized cards for that computer system. If the BIOS detects an unauthorized card, the BIOS will prevent boot of the system. This method allows the manufacturer to enable a system to accept several different 802.11b WiFi cards from different suppliers. This approach also enables wireless-ready systems, where the computer system is shipped with the antenna embedded in the cover and the end user is able to install one of the authorized 802.11b WiFi mPCI radio cards.
Unlike the FCC regulation of its 802.11b (ISM 2.4 GHz band) counterpart, the FCC's regulation of transmitters operating with the 802.11a (U-NII/5 GHz band) protocol requires that: “Any U-NII device that operates in the 5.15-5.25 GHz band shall use a transmitting antenna that is an integral part of the device.” (FCC regulation Part 15.407d). This restrictive requirement presents a challenge for integrating U-NII wireless LAN (WLAN) devices such as an U-NII wireless card in a mobile PC, which is designed with an antenna subsystem separate from the feature card implementing specific WLAN function. The BIOS Lock method for 802.11b (ISM 2.4 GHz band) is not stringent enough and does not meet this FCC standard of “integral part of the device”.
Conventional methods provided as solutions to the “integral part of the device” requirements either (1) solder (or otherwise permanently attach) antenna leads to the WLAN feature card, or (2) permanently “bury” the feature card inside the mobile PC behind tamper-proof screws or other such mechanisms. Both approaches are not ideal because of serviceability issues, manufacturability issues, and additional costs. More importantly, the permanence of the placement of the card eliminates the ability to provide U-NII-based cards as an after-market upgrade that is customer installable, as is currently possible with 802.11b cards. The Tamper Proof Screw, introduced by IBM is one hardware implementation that has received approval by the FCC for U-NII-based machines.
The PC industry has a long tradition of providing flexibility and expandability. Manufacturers, such as IBM, are extending this tradition to the wireless arena, and are now building substantially all laptops with integrated antennas. With the 802.11b (ISM 2.4 GHz standard, for example, the user can order a card at time of purchase, add wireless, or change wireless cards in the future. This functionality, particularly the adding and/or replacing of the wireless card after purchasing the computer system, has led to the generation of customer replaceable unit (CRUable) wireless devices in the 802.11b arena.
Currently, the 802.11b radio is widely deployed in corporate enterprises and in public hot spots, such as hotels, airports, etc. Recently, manufacturers have began to deploy the higher performance 802.11a (U-NII) radio in corporate infrastructures where additional performance and capacity is critical. The difference in functional characteristics and cost of the two radios (i.e., the transmitter types) results in a different market (and/or user) for computer systems designed to support one of the two types of radio. Naturally, because of the above described regulations, computer systems supporting the 802.11a (U-NII 5 GHz) standard requires the U-NII radio be built in to and shipped/sold with the computer system, while the radios for computers supporting the 802.11b standard may often be provided after-market, as a separate user-replaceable component.
Because of the differences in users, operating parameters/restrictions, and customer demands, manufacturers conventionally manufacture single-mode wireless 802.11b cards with a radio or a combo card that contains both an 802.11b radio and separate U-NII radio. The combo (U-NII & ISM) cards are installed in the computer systems connected to the antenna with tamper proof mechanisms in order to satisfy the FCC's “integral” requirement. 802.11a/b combo cards or single function U-NII radios are not sold as a separate after-market product.
The present invention recognizes the limitations with implementing U-NII-based wireless computer systems, as well as the limitation of not enabling after-market upgrades of cards. The invention further recognizes that it would be desirable to provide mechanisms that meet the “integral part of the device” requirement for the U-NII antenna connection, but still allows for serviceability and after-market replacement or addition. These and other benefits are provided by the invention described herein.